This PR improves CFiniteElementVec, and it contains
1) removed the negative value option of the Biot's constant.
2) in the assembly of the pressure coupling related RHS and matrix,
replaced the element constant saturation with node saturations,
changed the computation of pressure coupled matrix for the staggered scheme for H2M, and fixed a bug for the monolithic scheme of H2M
removed the restriction of pore pressure to be positive in the total stress calculation.
3) fixed the excavation conditions for the time stepping excavation model.
4) replaced `int CFiniteElementVec::Flow_Type``with an enum variable.
5) made some variable declarations local.
6) removed some repeated or unused source code.
The changes in 2) improves the computation solutions of the benchmarks for the THM coupled processes. Therefore the reference results of the affected benchmarks have to be updated too.
This PR improves CFiniteElementVec, and it contains 1) removed the negative value option of the Biot's constant. 2) in the assembly of the pressure coupling related RHS and matrix,
The changes in 2) improves the computation solutions of the benchmarks for the THM coupled processes. Therefore the reference results of the affected benchmarks have to be updated too.